Polyconducting device and applications therefor

ABSTRACT

A polyconducting device, both two terminal and three terminal, is shown which includes a metallic oxide or metallic salt and conducting members operatively connected thereto. Various applications of the device, including use as an oscillator, a gated oscillator and a modulation device are also shown.

United States Patent 1 1 [111 3,731,249 Lipsicas et al. 1 May 1, 1973 541 POLYCONDUCTING DEVICE AND 2,258,646 10 1941 011811318 ..252 519 APPLICATIONS THEREFOR 2,720,573 10 1955 Lundqvist ..252 519 x 2,735,824 2/1956 Haayman et al ..252/5l9 1 lnvemorsi MaXPiPswaS, Rlverdale; Damel 2,935,712 5/1960 Oppenheim e161. ..338/325 x Maths, Scarsdale, both of 3,394,030 7/1968 Clark ..338/308 i 3,474,305 10/1969 Szupillo ..338/3l4 X [73 1 Ass'gnee' Umversuy New York 3,487,338 12/1969 Matzelle et a]. ..317/234 x 22 Filed: Sept. 26, 1969 Prima ExaminerAlfred L. Brod 21 LN 861 380 Y 1 App 0 Attorney-Walton Bader [52] U.S. Cl ..338/325, 252/513, 307/299 A, [57] ABSTRACT 317/235 Z,332/16T,338/308,331/108 [51] Int. Cl. ..H0lc 1/14 A polyconductmg device: both two termma] and three 58 1 Field of Search ..252/513, 519; terminal, is shown which includes a metallic Oxide or 331/108; 338/325, 308, 309, 314; 332/16 T; metallic salt and conducting members operatively con- 307/306, 248, 249, 250,299 A; 317/234, nected thereto. Various applications of the device, in-

235, 40,133, 235 Z eluding use as an oscillator, a gated oscillator and a modulation device are also shown. 56 R fe n C! d 1 e re CBS 1 e 2 Claims, 11 Drawing Figures UNITED STATES PATENTS 2,237,006 4/1941 Koller ..338/308 X PATENTEDHAY 1 191a SHEET 1 UF 5 I 2/ POWER SUPPL Y mo 20 -"-7'ERM/NAL DEV/CE POWER SUPPL r INVENTORS Max Lipsiqus BY Daniel C. Mattis ,7 #04 A Attorney PATENTED HAY I 1975 SHEET 2 (IF 5 I I In I I, I I

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MAX LIPSICAS BY DANIEL C. MATTIS ATTORNEY PATENTEUHAY' 1 191alog L FIG.7I

F I G l I 2 3 4 5 Volts INVENTORS MAX LIPSICAS BY DANIEL c. MATTIS .5. MA 2 ATTORNEY PATENTEDHAY Hm 5,131,249

SHEET 0F 5 W IVolt per cm. 200 hz.

L L T T l0 Volts per cm. F l G 8 M I20 hz.

l0 Volts per cm.

IN VEN TORS 2 MAX LIPSICAS BY DANIEL C. MATTIS ATTORNEY PATENTEUHAY .1 1915 3731.249

SHEET 5 BF 5 F I G IO WWW- W W WW . F I G 9 V mv oRs MAX LIPSICAS BY DANIEL c. MATTIS ATTORNEY POLYCONDUCTING DEVICE AND APPLICATIONS THEREFOR DESCRIPTION OF THE INVENTION C. Mattis, Ser. No. 819,506, filed Mar. 18th, 1969, now

abandoned.

The polyconducting device of this invention comprises a metallic oxide, or a metallic salt as will be subsequently explained. The material may be disposed between two elements, which may be conducting, nonconducting, opaque or translucent; it may be deposited as a film on a suitable substrate, or it may be produced upon a substrate made of the metal of which the oxide is composed by appropriate chemical action. The mode of deposition of the substrate or materials used, will depend upon the application thereof as will be subsequently explained.

The device of this invention can be applied to various electronic applications and produces unusual and unexpected results.

The invention will now be further described by reference to the accompanying drawings which are made a part of this invention.

FIG. 1 is a cross-sectional view of a two terminal device variation of the polyconducting device of this invention.

FIG. 2' is a plan view of a multi-terminal variation of the polyconducting device of this invention made from mild steel rod.

FIG. 3 is a cross-sectional view of the device shown in FIG. 2 taken along lines 33 of FIG. 2.

FIG. 4 is a diagramatic view of an experimental device utilized to determine the I-V characteristics of the polyconducting device of this invention.

FIG. 5 is a diagrammatic view of a three terminal device utilized as an oscillator.

FIG. 6 is a graphic representation of the I-V characteristics found in utilizing the device diagramatically shown in FIG.4. 1

FIG. 7 is a plot of log l/V against V at liquid nitrogen temperatures utilizing the structure shown in FIG. 4.

FIG. 8 is a photograph of a typical set of wave forms obtained by the use of the oscillating device shown in FIG. 4.

FIG. 9 is a photograph of the output at Point B of FIG. 5 utilizing the device shown in FIG. 5.

FIG. 10 is a photograph of the output of the device as shown in FIG. 5 with the polyconducting device of this invention used as a modulation device.

FIG. 11 is a photograph of the output of the gated oscillator utilized in connection with this invention.

The invention will now be further described by reference to the specific form thereof as shown in the accompanying drawings. In this connection, however, the reader is cautioned to note that such specific form of this invention as shown in the specification herein is for illustrative purposes and for purposes of example only. Various changes and modifications could obviously be made without departing from the spirit and scope of this invention.

In FIG. I, there is shown a diagrammatic two terminal polyconducting device of this invention. This includes a pair of metallic contact blocks 11 and 12, which contain a metallic oxide or metallic salt powder 13 disposed therebetween. The metallic oxide, as previously discussed, may be those of transition series elements and rare earth elements (atomic numbers 21 through 29, 39 through 46, 71 through 78 and 89 and higher and the Lanthanides). As illustrative of the metallic oxides involved iron oxide (Fe O.) is mentioned. Others are the oxides of Sc, Ti, V, Cr, Rn, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ly, I-If, Ta, W, Re, Os, Tr, Pt, Ac, Th, Pa, U, La, Ce, and Eu. The metallic salt used may be the nitride, sulfate, sulfides and any other compounds of the above elements that will block the S and P elections or the metal. Specific desired characteristics can also be obtained by controlling the Mott transition point by doping the oxides or salts by addition, for example, of donor impurities which will contribute or trap charges and thus will vary the'Mott transition point.

However, the experimental work of this invention was performed utilizing Iron Oxide (Fe O The powder is unstable at room temperature and the maximum (stoichiometiric) purity is only 87 percent. A thin layer of this powder 13 was sandwiched between the polished surfaces of two steel gauge blocks 11 and 12 and this device (FIG. 1) was taped together with scotch tape and place in liquid nitrogen. The D.C. re-, sistance of the device at room temperature was, approximately, 2,000 ohms.

Other devices have been fabricated from mild steel rod and are illustrated in FIG. 2. A diameter disc 14, 1/16" thick, with one highly polished (front) face 15, is oxidized by heating in a moist oxygen atmosphere. Copper leads 16, I7 and 18 are attached to the oxidized front face 15 using indium solder and silver paste. A copper lead 18 is soft soldered to the (back) steel substrate. This produces a multi-terminal device. Experiments on other iron oxide powders (e.g. Fe 0 and FeO) have determined that the active ingredient in all our experiments is Pe o since this is the only iron oxide which shows stable electronic switching and negative resistance characteristics, provided the temperature is kept below 119 K. When the disc devices are left overnight at room temperature, there is a tendency for the switching voltage and resistivity in subsequent experiments at liquid nitrogen temperature to be different to that of the initial experiments. We believe this is due to changes in the stoichiometry of our films (oxygen diffusion and similar operations). This process is also enhanced by the presence of the steel substrate.

Specific examples of the utilization of the polyconducting device of this invention in various practical examples are set forth herein.

DETERMINATION OF l-V CHARACTERISTICS OF A TWO TERMINAL DEVICE The two terminal device of FIG. 1, diagramatically shown in FIG. 4 as 20, was connected to a variable voltage D.C. power supply 21 and a load resistor 22. The circuit was completed utilizing conductors 23, 24, and 25. As shown in the graph of FIG. 6 of a typical I-V plot characteristic switching is evident at A. A large load resistor (of order 30K) was used so as to ensure that the load line did not cut the I-V characteristic at more than one point for each setting of the D.C. power supply. Nevertheless, discontinuities in the l-V characteristic are evident at B and C, i.e. as the power supply voltage is raised, discontinuous changes in the current-voltage values are experienced at B and C, no matter how slowly the power supply voltage is changed. We believe the regions B and C represent evidence for first order micro-phase transitions and are analogous to a Maxwell construction on a critical curve (e.g. the vapor-liquid coexistence curve in the critical regime). The region between B and C represent a stable negative resistance region (voltage across the device is dropping as the current increases).

I-V characteristics for out devices have also been obtained at frequencies up to approximately 600 Khz, a power-oscillator replacing the DC. power supply in this case. In all cases the I-V characteristic is symmetrical about the origin, i.e. the characteristic is bi-polar. A further aspect of the I-V characteristic which should be noted is the hysteresis, typical of a first order phase transition, between the curve obtained as the power supply voltage is increased from zero to the conducting state and that obtained for the reversal from the conducting state to the insulating state.

A plot of log I/V versus V at liquid nitrogen temperature, for one of our sample discs, is shown in FIG. 7.

POLYCONDUCTING DEVICES UTILIZED AS OSCILLATORS The negative resistance characteristic of the polyconducting device, after switching has occurred, allows the device to be used as a relaxation oscillator. In the simplest case (the two terminal device of FIG. 1), the power supply voltage is set so that the device is biased stably at a point on the negative resistance characteristic. The oscillation frequency increases as the bias point is moved from a point near B (on the I-V characteristic (FIG. 6) towards the region C. At each setting of the bias, the device oscillates at a particular frequency, the range of oscillation possible with our disc devices being, approximately, 300 Khz to Mhz. The highest observed frequency with such a device was 10 Mhz. Lower frequencies can be readily obtained by the addition of an external capacitor across the device. A typical set of waveforms obtained with the device of FIG. 1 is shown in FIG. 8. The lowest frequency here was 80 hz and as the bias point was moved to lower voltage, the waveform is observed to decrease in amplitude and become more nearly sinusoidal, since the voltage excursion during oscillation is now limited to the region between the fixed bias point and the discontinuity C (FIG. 6).

FIG. 3 is a diagramatic view of a multi-terminal device (here shown as a 4 terminal device). The conductive substrate 26 bears a contact 27 secured to one face 32 thereupon.

At the opposite face is a metal oxide layer 28, to which are secured contacts 29, 30 and 311. Contacts 29 and 30 are more than a few millimeters apart and therefore the device can be considered to be a pair of separate two terminal devices between conductors 27 and 29 and conductors 27 and 30. Using appropriately set bias voltages through separate load resistors and separate power supplies, with the power supply common being returned to conductor 27 in each case, oscillations will be observed at 29 and 30, the oscillation frequency of 29 being independent of that at 30.

On the other hand, conductors 30 and 31 contact oxide layer 28 at a point less than a few millimeters apart. Therefore there will be interaction between the conductors 3t) and 3311 producing a number of highly interesting electric effects.

In FIG. 5 there is shown a three terminal device which includes tenninals A, B and C. Terminals A and B are connected through a load resistor 33 to a power supply 34. The circuit goes from terminal a through conductor 35, resistor 33, conductor 36, power supply 34, conductor 37 and contact B. Element 38 is a three terminal device similar to that of FIG. 3 but with conductor 31 and its contact point eliminated. Back contact C is either a passive pick-up point or an active injection point and is connected to conductor 39. If C is merely a fixed passive pick-up point, then the device is a two terminal device and the differentiated and clipped oscillator voltage from the device AB is observed at C.

POLYCONDUCTING DEVICE AS A MODULATION DEVICE In FIG. 5, if the power supply is set so that VAB is in the negative resistance region and oscillations are observed at B, the application of a voltage VCA, positive modulation maybe achieved; the application of saw toothvoltage at C, comparable in peak magnitude to VBA, has been observed in a typical case to provide a range of frequency modulation from 300 Khz to 5 Mhz. A photograph of the output at B is shown in FIG. 9. It is also possible to cause frequency entrainment (or locking:- the application'of a 4Mhz signal at C, to a bi-termin'al oscillator AB oscillating near I Mhz is shown in FIG. 10 to have caused the relaxation oscillator AB to adjust its frequency to an exact'subharmonic of 4 Mhz, namely 1 Mhz. Amplitude modulation and mixing have also been observed using a modulation voltage applied at C.

POLYCONDUCTING DEVICE UTILIZED AS A GATED OSCILLATOR It is also possible to bias the polyconducting device of this invention just below the switching voltage, i. e. in the insulating state, or just above the negative resistance region, in the conducting state. The applica- I tion of a gating voltage at C will switch the device into oscillation by modifying the bias voltage so as to bring it into the negative resistance region. In FIG. 11, we show the gated oscillator output obtained with a sinusoidal gating voltage VAC. VAC was applied at C to a polyconducting device biased so that VAB was just below the switching voltage. Similar photographs of gated oscillator outputs have been obtained, with gating applied during the negative half cycle of the sinusoidal gating voltage to a polyconducting device biased just above the negative resistance region. Square wave gating pulses have also been used, and in this case the oscillation frequency is, of course, constant and the oscillator sequence is precisely timed.

The foregoing sets forth the manner in which the objects of this invention are achieved.

terminal and said third terminals being greater than a few millimeters while the distance between components of said third terminals being less than a few millimeters.

2. A polyconductive device as described in claim 1 said substrate being iron and said metallic oxide being Fe O 

2. A polyconductive device as described in claim 1 said substrate being iron and said metallic oxide being Fe3O4. 